The Sharks-Part One 309 



amazing Thresher shark gets its food. The Thresher's prodigious tail- 

 often as long as the rest of its body— is apparently its principal means 

 of obtaining food, for its jaws and teeth are relatively weak. A Thresher 

 has been seen lashing a small fish again and again to kill or stun it so 

 that it could be swallowed. It is the only shark known to use its tail in 

 this way. 



The Thresher pursues schools of mackerel, bluefish, shad, menhaden, 

 bonito, and various herrings. When it nears a school of fish it splashes 

 the water with its tail, driving the fish into a close-packed crowd and 

 makinor smaller and smaller circles around them. Then, when the fish 

 are jammed together in a frightened mass, the Thresher darts among 

 them, mouth agape, and swallows them. Sometimes Threshers, work- 

 ing as a team, herd the fish between them and, at the moment of 

 slaughter, share the meal. The Thresher's odd form of preying is very 

 efficient. Twenty-seven mackerel were found in one \3y2-ioot Thresher. 



Threshers have supposedly joined with swordfish to attack whales— 

 the Thresher beating the whale with its tail and the swordfish stabbing 

 it. This tale has about as much foundation as stories about snakes that 

 form themselves into hoops to roll downhill. Tall stories about the 

 Thresher slapping whales to death probably are based on long-range 

 observations of genuine attacks on whales by the vicious Killer whale 

 {Orc'mns orca), which has a high dorsal fin and, as it clings by its teeth 

 to its struggling victim, raises great splashes. 



Threshers are known to grow to 20 feet or more, including tails. 

 They weigh up to 1,000 pounds. The Thresher is a pelagic fish, but it 

 often comes near to shore when it is corralling prey. Threshers seem 

 to stay near the surface, and they have been seen making spectacular 

 leaps out of the sea. 



Around the end of June, when the porgies are running near Block 

 Island, Rhode Island, Threshers are usually the most common shark 

 found in those waters, to the chagrin of commercial fishermen whose 

 nets are often ruined by struggling Threshers which have blundered 

 into them. 



The range of A. vulpinus extends from Ireland to the Cape of Good 

 Hope and the Mediterranean on the east, and from Nova Scotia and 

 the Gulf of St. Lawrence to northern Argentina on the west. It is also 

 found in the Pacific and the Indian Oceans, but ichthyologists are not 

 certain whether these reports involve A. viilp'miis or the similar Thresher 

 known in the Pacific (Alopias pelagicus Nakamura, 1935). Along the 

 eastern Pacific, Threshers are found from British Columbia to Chile. 

 Elsewhere in the Pacific, they are also known around Japan, Korea, 

 China, the Hawaiian Islands, New Zealand, and Australia, 



The Thresher's enormous tail distinguishes it from all other sharks. 



